Fiber optic cables are widely used to transmit communications signals over relatively long distances. A typical fiber optic cable includes a central core including a plurality of buffer tubes each, in turn, containing a plurality of individual optical fibers. The core also typically includes a central strength member. An outer plastic jacket may be provided over the core. Some cables may include a metallic layer beneath the plastic jacket to prevent rodent damage. Another type of cable includes optical fiber ribbons within an overall sheath. Each ribbon includes a plurality of individual fibers joined together in side-by-side relation.
Although an optical fiber cable can carry signals over relatively long distances without requiring repeaters, one common architecture includes one or more drop locations along a main cable route. In other words, it may be desirable to connect certain fibers to drop cables along the main cable route. Each such drop or splice point requires the protection of the cable ends and individual splices. More particularly, a splice closure is typically provided for terminating the cables and storing the splices.
U.S. Pat. No. 4,679,896 to Krafcik, for example, discloses a so-called butt splice closure wherein the ends of two cables to be spliced together are routed through one end plate of a generally cylindrical housing. The housing is provided by a pair of generally circular end plates, and a tubular cover connecting the two end plates. Raychem, the assignee of the present invention also manufactures butt splice closures wherein the cables to be spliced are brought in from a single end of the housing. A series of pivotally mounted splice organizers are provided. The pivotally connected splice organizers permit organizers to be moved to a raised position to facilitate access to an underlying organizer. A fixed slack basket may be positioned under the splice organizers to store slack buffer tubes, for example.
Another general type of splice closure is the in-line closure wherein cables enter the overall housing from opposing ends. An in-line splice closure may be particularly desirable for a drop or branch cable location where the main cable includes a significant number of fibers that can pass through the closure without requiring splicing. Only those fibers that need to be dropped are spliced and the remaining fibers can be stored within the housing.
For example, U.S. Pat. No. 4,805,979 to Bossard et al. discloses such an in-line fiber optic splice closure. The closure includes two mating shell portions which are secured together to define an overall protective housing. Cable entry ports are provided at each end of the housing and are defined by arcuate wall portions between the base and cover housing portions. A slack storage area is defined in the base by a pair of inwardly extending retaining brackets connected at a medial portion of the base. The cable ends are terminated adjacent the cable ports. A series of splice organizers are connected to the base above the slack storage area. Each splice organizer stores a number of individual fiber splices.
Unfortunately, access to the slack after the splice organizers are secured is restricted. The splice organizers must be carefully removed to prevent damage to the fibers to gain access to the stored slack. Re-access is typically required to add additional fiber drops, for example, such as to add a new user or increase the capacity of an existing user.
A splice closure is also desirably relatively compact and rugged for installation in any of a number of locations, such as in a manhole, on a supporting pole, or direct buried. A compact closure may also be less expensive to manufacture, since less materials may be required.